1. Field of the Invention
The present invention relates to chemical mechanical polishing (CMP), and a method for manufacturing a semiconductor device using the same.
2. Description of the Related Art
CMP is widely used as a method for planarizing surfaces of layers and/or multi-layers during a manufacturing process of a semiconductor device. In CMP, a disk on which a CMP pad is attached is rotated, slurry is supplied to an upper end of the CMP pad, a wafer fixed on a wafer carrier is allowed to contact a surface of the CMP pad and rotate, so that a surface of a wafer is planarized using friction and a chemical component of the slurry.
Numerous fine grooves are formed in a surface of the CMP pad (which is generally formed of polyurethane) to cause friction against a wafer surface, thereby performing a polishing operation, and allow the slurry to be swiftly supplied.
As the polishing of the wafer is performed successively, abrasive particles or other kind of foreign substances contained in the slurry remain in the grooves or the grooves are worn out, which changes the surface of the CMP pad. When the CMP pad changes, a wafer-polishing degree (i.e., a polishing rate) reduces, so that a process for reproducing the surface of the CMP pad (referred to as “conditioning”) is required.
During a conditioning of a CMP pad, a surface of the CMP pad is rubbed using a CMP pad dresser on which a diamond is attached, so that a changed surface state of the CMP pad is restored to an initial state.
A polishing degree during CMP can be known by optically measuring a thickness of a layer before and after a polishing operation. In this case, a problem can occur or be generated when optically measuring a thickness of the layer, and thus an error can occur.